New Biological and Chemical Evidences of Two Lamiaceae Species (Thymbra capitata and Thymus sipyleus subsp. rosulans): In Vitro, In Silico and Ex Vivo Approaches

Abstract

In this study, the methanolic and infusion extracts of two species, Thymbra capitata and Thymus sipyleus subsp. rosulans, were tested for their chemical composition and biological abilities (antioxidant, enzyme inhibitory and anti-inflammatory effects). The extracts yielded total phenolic and flavonoid contents in the range of 83.43-127.52 mg GAE/g and 9.41-46.34 mg RE/g, respectively. HPLC analysis revealed rosmarinic acid to be a major component of the studied extracts (15.85-26.43%). The best ABTS radical scavenging ability was observed in the methanol extract of T. capitata with 379.11 mg TE/g, followed by in the methanol extract of T. sipylus (360.93 mg TE/g). In the CUPRAC assay, the highest reducing ability was also found in the methanol extract of T. capitata with 802.22 mg TE/g. The phosphomolybdenum ability ranged from 2.39 to 3.61 mmol TE/g. In terms of tyrosinase inhibitory effects, the tested methanol extracts (83.18-89.66 mg KAE/g) were higher than the tested water extracts (18.74-19.11 mg KAE/g). Regarding the BChE inhibitory effects, the methanol extracts were active on the enzyme while the water extracts showed no inhibitory effect on it. Overall, the methanolic extracts showed better enzyme inhibition compared to the infusion extracts. Molecular docking also showed the selected exhibited potential binding affinities with all enzymes, with a preference for cholinesterases. Additionally, the extracts were effective in attenuating the LPS-induced increase in COX-2 and IL-6 gene expression in isolated colon, thus indicating promising anti-inflammatory effects. The preliminary results of this study suggest that these species are good natural sources of antioxidants and also provide some scope as enzyme inhibitors, most likely due to their bioactive contents such as phenolic acids, and thus can be exploited for different applications related to health promotion and disease prevention.

Keywords: Thymbra capitata; Thymus sipyleus subsp. rosulans; anti-inflammatory; antioxidant; enzyme inhibitors; flavonoid; phenolic.

Figure 1

Binding energy (docking) scores of the phytochemicals from Thymbra capitata and Thymus sipyleus subsp. rosulans extracts.

Figure 2

Protein–ligand interaction: (A) AChE and salvianolic acid K, (B) BChE and lithospermic acid A, (C) tyrosinase and rosmarinic acid, (D) amylase and vicenin-2, and (E) glucosidase and salvianolic acid B. The bioactive compounds were extracted from Thymbra capitata and Thymus sipyleus subsp. rosulans.

Figure 3

Inhibitory effects of Thymus sipyleus and Thymbra capitata extracts (100–300 µg/mL) on LPS-induced COX-2 gene expression, in isolated colon (ANOVA, p < 0.0001; *** p < 0.001 vs. LPS).

Figure 4

Inhibitory effects of Thymus sipyleus and Thymbra capitata extracts (100–300 µg/mL) on LPS-induced IL-6 gene expression, in isolated colon (ANOVA, p < 0.0001; *** p < 0.001 vs. LPS).